By Jelani Scott Celtics star Jaylen Brown found himself in unfamiliar territory Friday night after a pair of arguments with officials led to the first ejection of the eight-year veteran’s career. Brown’s surprising penalty occurred as the Celtics led the Knicks, 119-107, midway through the fourth quarter in Boston. A reach-in foul called on Brown as he guarded Knicks guard Immanuel Quickly sparked an animated response and a short argument immediately resulting in a technical foul. As New York shot the technical free throw, Brown continued arguing over the call before he was subbed out the game…